Attempt to fix uninstallation of zipped eggs

Author: sbidoul

src/pip/_internal/metadata/base.py

@@ -231,7 +231,9 @@ def installed_as_egg(self) -> bool:
         location = self.location
         if not location:
             return False
-        return location.endswith(".egg")
+        # XXX if the distribution is a zipped egg, location has a trailing /
+        # so we resort to pathlib.Path to check the suffix in a reliable way.
+        return pathlib.Path(location).suffix == ".egg"
 
     @property
     def installed_with_setuptools_egg_info(self) -> bool:

src/pip/_internal/req/req_uninstall.py

@@ -505,10 +505,13 @@ def from_dist(cls, dist: BaseDistribution) -> "UninstallPathSet":
             # package installed by easy_install
             # We cannot match on dist.egg_name because it can slightly vary
             # i.e. setuptools-0.6c11-py2.6.egg vs setuptools-0.6rc11-py2.6.egg
-            paths_to_remove.add(dist_location)
-            easy_install_egg = os.path.split(dist_location)[1]
+            # XXX We use normalized_dist_location because dist_location my contain
+            # a trailing / if the distribution is a zipped egg
+            # (which is not a directory).
+            paths_to_remove.add(normalized_dist_location)
+            easy_install_egg = os.path.split(normalized_dist_location)[1]
             easy_install_pth = os.path.join(
-                os.path.dirname(dist_location),
+                os.path.dirname(normalized_dist_location),
                 "easy-install.pth",
             )
             paths_to_remove.add_pth(easy_install_pth, "./" + easy_install_egg)